Ferroelectricity induced by spin-dependent metal-ligand hybridization in Ba$_2$CoGe$_2$O$_7$

TL;DR

This study reveals that in Ba$_2$CoGe$_2$O$_7$, ferroelectricity is induced by spin-dependent p-d hybridization rather than traditional models, enabling electrical control of magnetization.

Contribution

It demonstrates that spin-dependent p-d hybridization, influenced by spin-orbit interaction, causes ferroelectricity in Ba$_2$CoGe$_2$O$_7$, providing a new mechanism beyond conventional theories.

Findings

Ferroelectric polarization varies with magnetic field direction and magnitude.

Spin-dependent p-d hybridization explains ferroelectricity better than existing models.

Electrical control of magnetization is achieved through polarization manipulation.

Abstract

We have investigated the variation of induced ferroelectric polarization under magnetic field with various directions and magnitudes in a staggered antiferromagnet Ba$_2$CoGe$_2$O$_7$. While the ferroelectric polarization cannot be explained by the well-accepted spin current model nor exchange striction mechanism, we have shown that it is induced by the spin-dependent $p$-$d$ hybridization between the transition-metal (Co) and ligand (O) via the spin-orbit interaction. On the basis of the correspondence between the direction of electric polarization and the magnetic state, we have also demonstrated the electrical control of the magnetization direction.